Sorry for the lack of activity, I've been recovering since that awesome concert I last talked about.
I made mention of this a while ago but never gave an embed. That and I truly believe this deserves another mention. The pilot episode for Adventure Time that aired before the shows actual starting date. The animation is a bit different than what it is now, and yes the show is still airing and is due for another season. The next episode airs today at 10:30EST on Nick. Whoever thought this show was meant to air on a children's network or be seen by children in general clearly isn't in the best state of mind.
On a more sane note, check out the credits song called "Island Song" by Ashley Eriksson. This version isn't the exact same as in the show but it's practically the same.